Uma Thurman

"I was so surprised at how many things seemed new again," Thurman told Net-a-Porter in February 2014 after welcoming her third child, daughter Luna, in 2012 at age 42. (The actress is also mom to daughter Maya, born in 1998, and son Levon, born in 2002, with ex-husband Ethan Hawke.) "You're a different person. When you have a child in the early side of your child-bearing years -- which for a New Yorker means there's still a two in front of your age, as opposed to a three or a four -- you're changing so much as a person; you're so volatile. You think you're grown up, but you're a child yourself."